<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>设置图像的不透明度</title>
		<style>
			img{
				opacity: 0.3;
			}
			img:hover{
				opacity: 1;
			}
		</style>
	</head>
	<body>
		<img src="../img/约定.png" alt="" />
	</body>
</html>